Instead of editing the source code, I recommend you upload via your ftp program.
For example when you want to upload and restore or just upload content into a course go to:
The 12 represents the code number for your course, if you do not know the code number just upload an unique file to your course directory. Then locate it by browsing the different folders and start your upload.
The files you want will now be accessible in your course (these instructions based on using the Moodle Book function).
If you do not have FTP Access you will need to work with your Moodle Hosting provider to update your limit by following these instructions:
All the best,